TeX джерело:

A_{13}\,=\,\left|\begin{array}{rr}3&0\\2&1\end{array}\right|=3,\;\; A_{23}\,=\,-\,\left|\begin{array}{rr}1&2\\2&1\end{array}\right|=3,\;\; A_{33}\,=\,\left|\begin{array}{rr}1&2\\3&0\end{array}\right|=-6,\;\;